Bushing insulator



July 24, 1934. A. o. AUSTIN BUSHING INSULATOR 3 Sheets-Sheet 1 FiledMarch 5, 1931 .mll

E E Il: mr nu E 1N VENTQR Arf/wr 0. Ausf/f7. el Q Eg y //M A TTORNE YJuly 24, 1934. A. o. AUSTIN BUSHING INSULATOR Filed March 5, 1931 3Sheets-Sheet 2 3 f /1/ f, f

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July 24, 1934. A Q AUSTIN 1,967,653

BUSHING INSULATOR Filed Maron 5, 1951 s sheetS-sheet s [1V l/ENTOR v CTA TTORNEY Patented July SM, i234 i i y i.

USG MS'UMTH,

Jersey Application March 5, 1931i, Serial No. .52@,266 Y 23 Claims.

This invention relates to bushing insulators and has for one of itsobjects theprovision of means for discharging the filling fluid from theinterior of the bushing insulator without the necessity of reaching thelower end of the insulator.

A further object of the invention is to provide means for maintainingthe insulator at a constant temperature.

Other objects and advantages will appear from the following description.

The invention is exempliiied by the combina'- tion and arrangement ofparts shown in the accompanying drawings `and described in the followingspecification, and it is more particularly pointed out in the appendedclaims. i

In the drawings:

Fig. 1 is an elevation with parts in section showing one form of thepresent invention.

Fig. 2 is a part section and part elevation of the upper end of aninsulator having a modied form of the invention applied thereto.

Fig. 3 is a part section and part elevation of the lower end of theinsulator corresponding to Fig. 2.

Fig. 4 is a view similar to Fig. l showing a different form of theinvention.

Fig. 5 is a view similar to Fig. 1 showing still another form of theinvention.

1n high voltage bushings, particularly those filled with oil or otherfluid insulating medium, it sometimes becomes advisable to change thefluid when its dielectric strength is reduced by absorption oi water orconducting compounds caused by electrostatic discharges. This isparticularly true where the insulating batlies or cylinders in a bushingare made of material which will take up moisture or which will carbonizedue to leakage or charging current.

It has been common practice to provide lling or emptying means at theiange of the bushing. Since, however, the oil of lowest dielectricstrength will be found at the bottom of the bushing, it is evident thatfilling from the flange will not re move the material of lowestdielectric strength.

llt is also diflicult to change the oil where it is necessary to get atthe lower end of the bushing, as where the bushing extends into a closedhousing. This will necessitate taking the bushing out of service andpossibly lowering the oil level in the housing to get at the lower endconnection. Where bushings are placed in a transformer housing, this isa serious matter and constitutes an increased hazard.

The present invention provides means for changing the oil in a bushing,which may be operated without reaching the inner or enclosed end of thebushing, and which will permit change of the insulating medium withouttaking the bushing out of service. The same means for changing themedium may also be used for obtaining a (Cl. NES-Jell) sample-of thefilling medium to see whether ci not a change is necessary or advisable.

1n the form of the invention shown in Fig. 1 the members 10 and 11 formthe outside case or insulating members of 'the bushing which en- 65close insulating baffle 12. The bushing is provided with a hollowconductor member 13 having a valve seat 14 pierced by an orifice l5.vThe orifice 15 is closed by a needle valve or other suitable closingdevice 16.' An opening 17 is pro- 70 vided in the wall of the conductor13 and in the side of the block forming the valve seat 14.

When it is desired to change the oil in the bushing it is not necessaryto go below the metal supporting iiange 18, as the weather cap 19 may 75be removed, exposing the rod 20 which is attached to or a part of theneedle valve 16. The valve 16 may then be opened by rotating the rod 20by means of a wrench or other suitable instrument applied to the head 21of the rod 80 20. This will permit the oil to be discharged through theopening l5. The oil may be replen ished through the lling plug 22 at theange, or through the filling plug 23 inthe expansion reservoir. ifdesired, the bushing may be entire- 35 ly emptied and refilled, or theoil changed, without lowering the level so as to avoid possible airtraps.

The same general principle applied in a differn ent form is shown inFigs. 2 and 3.. 1n this form 96 acentral pull rod 24 is used forattaching the lower terminal 25 with its conductor lead 26, so that abushing may be removed or installed in a transformer housing or otherapparatus without the necessity of lowering the oil level or Q5 reachingthe lower end of the bushing to attach vthe vterminal lead 26.

through the center of the bushing as the bushing i is lowered intoplace. After the bushing is in place, the pull rod 24 is tightened orplaced under tension, which insures good contact between the contactmember 28 at the lower end of the bushing and the terminal 25. Byplacing the gasket 27 between the removable terminal member 25 attachedto the lead 26 and terminal 28 attached to the bushing, it is possibleto effect a tight seal at this point. By providing an openn ing 29 inthe hollow conducting member 30, ll() oil may be discharged from thespace inside the bushing to the space between the pull rod 24 and theWall of the conducting tube 30. By loosening the pull rod 2li which willpermit terminal cap 25 to drop to bring the openings 3l in reg- 115istration with the groove 32, the oil may be discharged througli'openings 31 or suitable grooves permitting the bushing to be drained.The arrangement at the upper end of the bushing permitting lowering cithe pull rod 24 is shown in 12 `lfig. 2. @e rod 24 is provided with nuts33 for tightening the rod and holding it in place. These are readilyaccessible by removing the weather cap 34. The nuts 33 rest upon washers54 supported on the upper end of the conductor tube 30. The tube is'heldunder` tension by springs 35 resting on the bottom of the reser- Voir36.

Instead of draining the oil by opening the valve 16, the arrangementshown in Figs. 2 and 3 makes it possible to remove the oil from thebottom of the bushing through the upper end.

The cap 37 is provided with a plugged opening 38 and the terminal 3drhas an opening register ing with the opening 38. When it is desired toremove the oil from the bushing, the plug is removed from the opening 38and a connecting pipe inserted in its place. By applying suction to theconnected pipe by any suitable means such as siphoning, oil' will bedrawn up through the space between the draw rod 24 and the wall of theconducting tube 30. The washers 54 are provided with suitable grooves topermit upward iiow of the oil. The oil will be drawn from the lower endof the bushing through the opening 29. With this arrangement it is notnecessary to provide an opening at the lower end of the bushing so thedanger of leaks can be avoided.

If desired, the bushing may be entirely drained before refilling or afresh supply of oil allowed to enter at an opening in the fillingiiange, as shown in Fig. 1. A preferable method, however, is to removethe filling plug 39 in the reservoir 36 and allow the new oil to ow inthrough this opening as the old is withdrawn through-opening 38 so as tomaintain the oil level. If the new oil is warmer than the oil beingremoved, there will be but very little mixture of the two and a completechange of the oil may be elected in exceedingly short time.

In the form of the invention shown in Fig. li, the inner baffle 39 formsa tube through the bushing for the' removal of the oil. The upper end ofthe baille 39 is closed by cork or other suitable packing material 40through which an outlet tube 41 extends. The outer end of the tube 4lmay be closed by a cap 42. The lower end of the baiile 39 may be leftopen or provided with an extension 43 having its lower end open insidethe outer shell at its bottom end. With the construction shown in Fig.4, all that is necessary to replace the oil in the bushing is to removethe cap 42, attach suitable connecting means and apply the necessarysuction to draw the oil through the tubular members 39, 4l and 43. Thismay be accomplished by any suitable means such as a -siphon or suctionpump. A fresh supply of oil may be admitted through suitable openings orpassages 44 in the upper terminal or through the hole in the supportingange if desired.

Another form of the invention which may have a material advantage insome types where a central passage is not easily provided is shown inFig. 5 in which an insulating tube 46 extends to the bottom of thebushing and is connected at its upper end to a suitable outlet 47 at theange. This member 46 may be a'ber, porcelain, glass, or insulating tubemade of suitable material. In order to change the oil in the bushing,all that is necessary is to open the member 47 and allow the oil todischarge. A threeway valve 48 is provided for this purpose. If oil isfilled in through the upper filling plug 49, the oil may be readilychanged in the bushing inattesa even without taking the bushing out ofservice. Where the member 46 Within the insulator is formed ofdielectric material, the connecting conduit outside of the insulator maybe of conducting material. Where cil and Water are placed under highstress in a bushing, Water is sometimes precipitated. This tends toaccumulate in the lower end of the bushing. 1t is therefore advantageousto be able to withdraw the liquid from the lower end of the bushing. Theability to maintain a definite 'standard in the insulating oil has theadvantage that the electrical characteristics of the bushing will notchange materially. This is important where a capacitance coupling is tobe used and a high degree of accuracy maintained. The capacitancecoupling shown in Fig. 5 is similar to that of my prior Patent#1,910,228, dated May 23, 1933. The baffle 55 has a metallized surface56 forming an electrostatic coupling with the central conductor 57. Alead 58 extends out through the bushing 59 and is connected with theprimair C a transformer 60. The other terminal transformer primary isgrounded at 61. Charging current for the capacitance member 56 passesthrough the transformer primary. The secondary of the transformer isconnected to any electrical translating device to be energized such as ameter, relay or synchronizing apparatus.

The invention also has the advantage that means may be provided formaintaining a constant temperature in the bushing. In order to maintaina constant temperature in the bushing, connection 50 is provided betweenthe outlet 47 and an inlet 51. If the outlet 47 and inlet 5l areconnected to a suitable oil supply which may be circulated and in whichthe temperature may be controlled, it is evident that the temperaturcwithin the bushing may be controlled to practically any desired point.This may be readily effected by connecting the outlet 47 and inlet 51 bya tubular member 50 in such a Way that the oil may be warmed by aheating element 52, heat being supplied by an electric currentcontrolled by a suitable thermal relay 53. By heating the oil it ispossible to produce sufficient heat so as to force the circulation andthereby maintain the temperaturein the bushing. This temperature may becontrolled either through limiting the maximum amount by the relation ofradiation to heat supplied, or by the use of the relay which may beplaced in the circulating oil supply of the bushing at the bushing orelsewhere if desired.

By raising the temperature of the bushing above the air, the insulatingproperty of the bushing will be maintained and the danger of flashoverparticularly under fog and dirt conditions will be greatly reduced. Asystem of this kind may be used which may tend to heat up the bushingsthrough any suitable relay which may be actuated by humidity ortemperature, or through periods when it is desired to Warm the surfaceof the bushing or to maintain a definite temperature inside the bushingto control the electrical characteristics of the capacitance tap, or tomaintain high insulation of the oil to preventit taking up water.

I claim:

1. The combination with a bushing insulator, of means accessible atapoint above the lower end of said insulator for draining the fillingfluid from the interior of said insulator.

2. The combination with a bushing insulator having a flange between theAends thereof for supporting said insulator, of means accessible at apoint above said flange for draining the uid from the interior of saidinsulator.

3. The combination with a bushing insulator having a drain opening atthe lower end thereof, of a closure for said opening, and meansaccessible at a point above the lower end of said insulator for openingsaid closure.

4. The combination with a bushing insulator having a flange between theends thereof for supporting said insulator, said insulator having adrain passage at the lower end thereof, of a closure for said drainpassage, and means accessible at a point above said iiange for operatingsaid closure to open and close said drain passage.

5. The combination with a bushing insulator, of a conduit having anintake opening in the interior of said insulator near the lower endthereof, said conduit having a discharge opening adjacent the upper endof said insulator.

6. 'I'he combination with a bushing insulator having one end thereofadapted to extend into a closed housing, of a discharge conduit havingan intake opening within the interior of said insulator adjacent thelower end thereof and having an outlet opening at a point accessiblefrom the outside of said housing when said bushing insulator is in placein said housing.

rI. The combination with a bushing insulator having a flange thereon forsupporting saidv insulator in a housing, a conduit having an intakeopening in the interior of said insulator adjacent the lower endthereof, and an outlet opening outside oi said housing adjacent saidiiange.

8. The combination with a bushing insulator, of a drain pipe extendingthrough said insulator adjacent the axis thereof and having an intakeopening at the lower end of said insulator and an outlet opening at theupper end of said insulator.

9. The combination with a bushing insulator having one end thereofarranged to extend into a closed housing, and means forming a drain forsaid insulator having an intake opening within said insulator adjacentthe inner end thereof, and an outlet opening accessible from a pointoutside of said housing.

10. The combination with a bushing insulator having one end thereofarranged to extend into a closed housing, of dielectric material forminga drain for said insulator having an intake opening within saidinsulator and adjacent the inner end thereof and having an outletopening outside of said housing and below the upper end of saidinsulator.

l1'. 'I'he combination with a bushing insulator having a flange betweenthe ends thereof for supporting said insulator with one end thereofextending into a closed housing, dielectric means forming a drainpassage having an intake opening within said insulator and adjacent theinner end of said housing and having an outlet opening outside oi saidhousing and adjacent said flange.

i2. The combination with a bushing insulator having a drain conduit fordraining the nlling liquid from the interior of said insulator, saidconduit comprising a dielectric baille disposed within said bushinginsulator.

i3. A bushing insulator comprising a dielectric shell, a conductorextending through said insulator, Aa iiange secured to said insulatorbetween the ends thereof ior supporting said insulator with one endthereof extending into a closed housing, a tubular dielectric baillesurrounding said conductor, and an outlet opening having tightconnection with the interior of said baille and extending outsideof saidinsulator for withdrawing the nlling liquid from the interior of saidinsulator through said baiile.

14. The combination with a bushing insulator, of means for heating theinterior of said insulator to maintain a desired temperature therein andtemperature regulated means for controlling said heating means.

15. The combination with a bushing insulator having a capacitancecoupling connected therewith, of means for heating saidinsulator tocontrol the characteristics of said coupling.

16. The combination with a bushing insulator having a capacitancecoupling connected therewith, of means lling the interior of saidbushing insulator, and means for heating said filling material tocontrol the characteristics of said capacitance coupling.

17. The combination with a bushing insulator having a filling liquidtherein, of means for heating the liquid in said insulator to controlthe temperature of said insulator, and a thermal device within saidinsulator for controlling said heating means.

1s. The'combination with a bushing insulatcr having a capacitancecoupling therein, of a filling medium for said insulator forming atleast part of the dielectric element of said coupling, and means forheating said illling medium to control the electrostatic propertiesthereof and to prevent accumulation of moisture on the outside of saidinsulator.

19. 'I'he combination with a. bushing insulator, of lling fluid withinsaid insulator, a conduit having an intake opening adjacent the lowerend of said insulator, and an outlet opening above the lower end of saidinsulator, a second conduit having connection with the outlet opening ofsaid first-named conduit and having another connection with the interiorof said insulator, and means for heating and circulating the fillingfluid through said second-named conduit to control the temperature ofthe fluid within said insulator.

20. The combination with a bushing insulator, of a liquid filling mediumfor said insulator, of a conduit of dielectric material disposed withinsaid insulator and extending upwardly from the lower portion thereof andhaving an outlet to the exterior of said insulator, and a connectingconduit of conducting material outside of said insulator.

2l. The combination with a conductor, of means comprising a. member ofconducting material and a dielectric forming a capacitance coupling withsaid conductor, and means for regulating the temperature of saiddielectric for controlling the electrical characteristics of saidcapacitance coupling.

22. The combination with a bushing insulator, of a capacitance couplingcomprising a dielectric within said insulator, and means for regulatingthe temperature of said dielectric for controlling the electricalcharacteristics of said capacitance coupling.

23. The combination with a bushing insulator, of an insulating fillingmedium for said insulator, a capacitance coupling connected with saidinsulator, and means for regulating the temperature of said fillingmedium to control the electrical characteristics oi said capacitancecoupling.

. ARTHUR O. AUSTIN.

